Endotracheal intubation is a procedure performed during the induction of general anesthesia. The patient is rendered unconscious with intravenous medications. With the patient asleep and paralyzed, the mouth is opened and a laryngoscope, which includes a handle with a light source connected to a straight or curved steel blade, is used to insert an endotracheal tube. The blade is inserted in the patient's mouth and the tongue is lifted and swept to the left side of the mouth. The blade is then further inserted to access the laryngeal structures and it is lifted in an upward motion to expose the vocal cords.
The light from the laryngoscope handle illuminates the vocal cords opening in order to see as the endotracheal tube is inserted into the trachea. This allows direct access to the lungs. At this point, a patient can be safely ventilated with oxygen and anesthetic gases and is kept asleep for a surgical procedure.
Laryngoscopy is not always a simple procedure. Patients have various anatomical differences that may complicate the insertion of an endotracheal tube. These complications range from devastating outcomes such as anoxia (lack of oxygen to the brain) to less life-threatening outcomes such as mouth and dental trauma. Dental trauma, in particular, is a common complication that occurs during the administration of general anesthesia.
Some patients have what is known as a “difficult airway”. That is, they may have short mandibles (no chin), small mouths, large tongues, prominent upper incisors and/or fat “bull” necks (double chin). Treating a patient with a difficult airway is when dental trauma occurs most frequently since the upper teeth are positioned very close to the laryngoscope blade when used to intubate the trachea for the induction of general anesthesia. When the laryngoscope blade is inserted into the mouth, the flange of the blade can come in contact with the upper teeth. If the airway anatomy is such that the space for pushing the tongue and laryngeal structure away from the vocal cords opening is small, then the practitioner may attempt to force the structures aside by using the upper teeth as a fulcrum and torque the laryngoscope blade in the effort to expose the vocal cords. This pressure on the upper teeth commonly results in chipped teeth, dislodgment of caps and bridges or complete breaking of one or more teeth. Although not a life threatening occurrence, this outcome has become a common reason for lawsuits against anesthesia practitioners.
In order to prevent this type of dental trauma, there have been modifications to laryngoscope blades to minimize damage to the teeth. The modified blades include curved and angled blades that allow for improved visualization with less torquing of the laryngoscope. However, the steel flange may still come into contact with the teeth.
Tooth guards, such as for example, sports guards, may also be used, however, they may not fit well and have the potential to move during intubation causing distraction and reduced visualization. Other devices have been used to prevent direct dental contact with the steel blade, however, these devices can be complex, cumbersome or can consume too much time or be impractical to apply in a real clinical setting, particularly during an emergency when ventilation is needed immediately.